1. Field of the Invention
This application is a 371 of PCT/JP 04/06999 May 5, 2004
The present invention relates to an electronic device having a function that receives a radio signal that sends prescribed information, including time information and displays or gives notification of as it displays the prescribed information, and that corrects the time information to accurate time information, and more particularly the present invention relates to an electronic device having improved radio signal receiving performance in the case in which a metal exterior part such as a metal case is used.
Additionally, more specifically the present invention relates to an electronic device configured so that performance of an antenna in receiving a radio signal does not worsen, even in the case in which a resonant antenna is in the vicinity of a metal object or is placed within a metal exterior part, and more specifically it relates to a radio controlled time piece in which an antenna is disposed within a metal exterior part.
2. Background Art
In recent years, many commercially made electronic devices, such as watches, mobile telephones, and radio communication equipment and the like, receive a standard radio signal having a long wave and including a time code therein, and have a radio-signal correction function which, during operation, automatically adjusts the time of a time-keeping circuit in the electronic device to the time of the standard time.
In the past, it is well-known that formats of displaying the time in a watch, which is a specific example of such an electronic device, include the analog method, in which the time is indicated by two or three hands, the digital method, in which an electro-optical device such as LCD or LED is used to indicate the time, and a combination method, which is the combination of the above-noted two methods.
Of these methods, among the analog time piece, it is also well-known that users can select it depending upon the likes of the user, for example, that based upon whether or not the time piece has a second hand or a calendar, and further can select it based upon whether or not the time piece has such secondary time-keeping functions as a chronograph function, an alarm function, and an age of the moon indicating function or the like.
In addition, while the accuracy of the electronic time pieces in the past was almost always determined by the accuracy of a circuit block such as the quartz oscillator within the movement, with the establishment in recent years of transmitting facilities in various countries for standard time radio signals, radio controlled time piece that enable automatic time correction by receiving these standard time signals have come into use.
With regard these radio controlled time pieces, there have been many patent applications in the past (for example, there is the Japanese Patent Examined Patent publication 11-304973 and the Japanese Unexamined Patent Publication No. 2001-33571).
In general, a radio controlled time piece automatically corrects for errors in the time kept by an internal counter in the time piece itself by receiving a standard time radio signal, as long as the time piece is in an environment in which it is possible to receive a radio signal, it is possible to bring the indication error of the watch hands extremely close to zero. The frequency and data format of the standard time radio signal is established by the transmitting facilities, and at present, in addition to Japan, there are transmissions in Germany and the US, for example, and radio controlled time pieces are widely used in those countries. The radio signal used in current radio controlled time pieces is a long-wave signal, because of the ability to cover a broad area with minimal transmitting facilities. Furthermore, to avoid interference at the borders between standard time radio signals in Japan, the two stations currently transmitting in Japan transmit on different frequencies, 40 kHz and 60 kHz.
Problems encountered in the past are described below, taking the example of a time piece having a radio-signal correction function (hereinafter called radio controlled time piece), which is a typical electronic device.
Specifically, a known radio controlled time piece receives a standard radio signal as noted above, this being a standard radio signal (carrier wave) that includes time information, and extracts time information from the radio signal, so as to obtain the accurate time. The radio signal including the time information differs in frequency depending upon the country and, for example as noted above in Japan, under the administration of the Ministry of General Affairs and Ministry of Posts, is transmitted as standard radio signals at 40 kHz and 60 kHz.
FIG. 20 is a block diagram showing the general functioning of a specific example of such a radio controlled time piece. This radio controlled time piece is formed by an antenna 1, a radio-controlled watch receiver 2, a CPU 3, a display drive section 4, and an input device 5 and the like.
In addition, although not shown in the drawing, the time piece includes hour, minute, and second hands, or a display section using a liquid-wind shield or the like.
In this radio controlled time piece, a radio signal including time information is first received by the antenna 1.
The receiver 2 of a radio controlled time piece amplifies and detects the radio signal received by the antenna 1, and extracts and outputs time information from the radio signal. The CPU 3 outputs the current time data, based on time information output from the receiver 2 of the radio controlled time piece. The display drive section 4, based on the current time data output from the CPU 3, causes the display section to indicate the current time. The input device 5 is used, for example, in inputting operation information such as resetting and the like, to the CPU 3.
The time information (time code) included in the radio signal is a pulse signal having a 60-second period and, although it varies depending on the country, in the case of Japan, it has one pulse riding thereon, each having either one of a width of 200, 500, or 800 ms each second. A combination of these pulses enables the acquisition of the time in 60 seconds. The CPU 3, by reading from the received pulse signal the pulse width of the pulse each 1 second, obtains the time information (current time). The CPU, using the obtained time information, corrects the time indicated on the display section via the display drive section 4. The radio controlled time piece, therefore, based on the received time information, corrects the indicated time each prescribed interval of time, thereby enabling an accurate display of time at all times.
A wristwatch, in which an antenna, a radio-controlled watch receiver, a CPU, a display drive section, and a display section are housed within a case, which is an antenna enclosure, has already been provided. In order for the antenna to receive radio signals, the material used for the case is usually an electrically non-conductive material, such as synthetic resin or ceramic. That is, if the antenna is housed within a case made of an electrically conductive material such as a metal, magnetic flux generated in the vicinity of the antenna is absorbed by the electrically conductive material, and the resonance phenomenon is hindered, resulting in a significant worsening of the receiving performance of the antenna.
FIG. 35 shows the general configuration of another specific example of an analog type radio controlled time piece.
Specifically, in FIG. 35, 101 denotes an antenna that receives a radio signal, 102 is a watch movement that drives hands, 103 is an outer case that houses the watch movement 102 and the antenna 101, 104 is a caseback, 105 is a watch dial having scales indicating the time, and 106 is a glass.
In FIG. 35, the antenna 101 is formed by an antenna core 101a having a high magnetic permeability, such as ferrite or an amorphous alloy, and a coil part 101b wound around the antenna core 101a, and is housed together with the movement 102 inside a closed space 107 formed by the outer case 103, the caseback 104, and the watch dial 105.
In this time piece, when a radio signal 109 that arrives by passing through the outer case 103 and passes through the antenna core 101a, a current is generated in the antenna coil part 101b. A circuit block (not illustrated), which is a constituent part of the watch movement 102, is electrically coupled to the two ends of the antenna coil part 101b, and the current generated in the antenna coil part 101b is sent to a circuit via this coupling part. The current sent to the circuit resonates at a frequency that is the same as a pre-established as the standard time radio signal and is filtered by a quartz resonator, the time information only being extracted therefrom by a decoding circuit (not illustrated).
In this case, the watch movement 102 has in its circuitry system a time-keeping counter for the time, separate from the above-noted time information. The watch movement 102 compares the time in accordance with the time-keeping counter and the filtered time information and, in the case in which there is a mutual difference therebetween, outputs a hand-correction instruction to a motor block (not illustrated), a motor being moved so that the hands are corrected to the time information from the standard time radio signal. By doing this, at the point in time at which the standard time radio signal is received, the time indicated by the time piece is corrected to the proper time.
In FIG. 35, however, the antenna 101 and the watch movement 102 are housed in the closed space 107 surrounded by the outer case 103, the caseback 104, and the watch dial 105, and the antenna 101 must receive the radio signal 109 from within this closed space 107.
For this reason, in FIG. 35 the outer case 103 and the rear case 104 are formed of a substance that has a high eddy current loss, such as typified by a high polymer resin. By doing this, the radio signal 109 is able to reach the antenna 101 housed within the closed space 107 without being attenuated by the outer case 103 and the caseback 104.
However, in the case in which the outer case 103 is formed of a high polymer resin, there is a significant loss of rigidity in comparison with the metals such as stainless steel and titanium used in usual watches. For this reason, in order to prevent breakage of the watch by dropping in normal use, it is necessary to make the material thickness of the outer case 103 and the caseback 104 greater than the case in which these are formed from metal, resulting in the problem of the watch itself becoming large.
A past example of an improvement on the above is shown in FIG. 36. FIG. 36 shows a plan view of an improved example of the past, in which elements that are the same as in FIG. 35 are assigned the same reference numerals and are not described herein. As shown in FIG. 36, there is a commercial production having a structure in which the outer case 103 and the caseback 104 are formed of metal, and an antenna case 110 made of a high polymer resin is fixed to a part thereof that is not superposed in overlapped condition in a planar manner with the metal outer case 103 and caseback 104, the antenna 101 sealed therewithin being coupled to the watch movement 102. In the case of this product, because the antenna 101 is disposed on the outside of the closed space 107 formed by the outer case 103, the caseback 104, and the watch dial 105, a radio signal 109 incident to the antenna 101 tends not to be affected by metal parts such as the outer case 103, thereby making it possible to receive the radio signal 109.
In this case, however, the shape of the finished time piece is particular special, and there is the problem that this seriously restricts the design of the finished time piece.
Additionally, because the mass feeling of the outer case 103 and the antenna case 110, which is made of high polymer resin, into which the antenna is sealed become large, this is difficult to accommodate with the design, and there is the problem that the design inevitably becomes one that is difficult for users to accept.
Additionally, in the case in which the outer case 103 and the caseback 104 are made of high polymer resin, there is the drawback of a worsened mass feeling in the texture in comparison with metal. Although it is possible to achieve a metallic gloss by performing surface treatment of the high polymer resin, there is still an undeniable deterioration in terms of gloss and mass feeling of the texture when compared with metal.
Although, in response to the above, there is a practically usable product in which, as shown in FIG. 35, only the part of a side of the watch dial 105 that is directly visible to the user, that is, the bezel 111, is made of metal, the outer case 103 and the caseback 104 on the side surface thereof being formed of high polymer resin, compared with a usual time piece with metal exterior parts, there is an increase in the overall thickness of the finished time piece, and a deterioration in the mass feeling of texture.
In the case of high polymer resin, plastic deformation tends to occur, for example, because of tightening the caseback 104, and there is a problem of water tightness a the joining part between the caseback 104 and the outer case 103, and there is the problem that it is not possible to include in a product group such time pieces as a diver's watch with high waterproofness.
Although, in response to the above, a practical product exists in which the case and caseback are formed of a material other than high polymer resin such as non-metallic material, for example ceramic, sintering is required to maintain the rigidity of ceramic and there is the problem of either not being able to achieve accurate processing after sintering or not being able to polish a complex shape, thereby imposing a serious restriction on design of the exterior parts. Additionally, because of the brittleness of ceramic, there is the problem of cracking and chipping caused by impact.
To avoid such antenna receiving problems, the use of a case made of synthetic resin not only leads to a loss of damage resistance and chemical resistance, but also to a loss of the attractive appearance and feeling of high quality that are required for a time piece that is an accessory. For this reason, a radio controlled time piece having a metal case has been proposed.
FIG. 21 is a cross-sectional view showing an example of the construction of a radio controlled time piece using metal in part of the case. The case 10 of this wristwatch is generally formed by a body 11, a caseback 12, and a wind shield 13. A movement 14 is disposed within the body, which is linked to a band (not illustrated), by a known means. A watch dial 15 and hands 16 are also disposed above the movement 14 by a known means. A bar antenna 17, which is a magnetic long-wave antenna, is disposed below the movement 14 so that it is positioned above the caseback 12. This bar antenna 17 is formed by a magnetic core member 18 and a coil 20 wound around the magnetic core member 18, and is fixed to the upper surface of a holding member made of synthetic resin.
The movement 14 has the above-described radio controlled watch receiving means, a CPU, and a display drive section, and is electrically connected to the bar antenna 17 by a conductor 21. Therefore, based on the standard radio signal received by the bar antenna 17, the CPU of the movement 14 causes a gear mechanism (not illustrated) in the display drive section to move, so as to drive the positions of the hands 16 of the display section so as to constantly correct them. In this description, the up and down directions are taken to indicate the up and down directions in FIG. 21.
The body 11 is made of a non-hollow, that is, solid, electrically conductive material, such as solid stainless steel. A wind shield 13 made of glass, which is an electrically non-conductive material, is fixed to the uppermost part of the body 11 by a known means such as an adhesive or the like. The watch dial 15 is made of synthetic resin or ceramic, which are electrically non-conductive materials. The caseback 12 is formed by an annular peripheral frame 22, made of stainless steel and fixed to the body 11, and an a glass 23 fixed to the inside of the peripheral frame 22. In this manner, although electrically non-conductive materials are visible at the upper and lower surfaces of the body of this wristwatch, because the side surface part of the case is made of metal, there is the advantage of not sacrificing the attractive appearance and high-quality feel of the time piece as an accessory (refer to, for example, Japanese Unexamined Patent Publication No. 2001-33571).
Specifically, as adopted in Japanese Unexamined Patent Publication No. 2001-33571, in the case in which the caseback is made of an non-metallic material such as typified by high polymer resin, glass, or ceramic, although there is the above-noted advantage, there are many restrictions in selecting the material, difficulty in manufacturing, and many problems in achieving a pleasing appearance as a finished time piece, making it desirable to form the caseback from metal.
For these reasons, there is a great restriction to the material of the exterior parts when developing a radio-controlled time piece in the past, and that meant that it was extremely difficult to make the finished time piece minimized.
In the subject radio controlled time piece, it is thought that the receiving performance is determined by the antenna characteristics and the receiving circuit characteristics.
That is, in the general technical knowledge of the past, the lower limit of the input signal of the receiving circuit or receiving IC was in fact approximately 1 μV in signal amplitude, and in order to achieve practical receiving performance it is necessary to obtain an output signal, the signal amplitude of which being approximately 1 μV with a an electrical field strength (radio signal strength) of 40 to 50 dBμV/m, as a signal receiving antenna.
For this reason, in the case in which there is a size restriction, a resonant type antenna, which can achieve a large signal output, was generally used.
Because the radio signal has a long wavelength a bar antenna with conductive wire being wound around a magnetic core is generally used as this type of antenna.
In a receiving antenna of this type, because the output of the receiving antenna is basically proportional to the size of the receiving antenna, in order to achieve practically usable receiving performance, it is not possible for the antenna to be excessively small, leading to the problem of receiving performance and placement in the case of a small time piece such as a wristwatch.
Additionally, the output of the receiving antenna drops dramatically when it is housed in a metal exterior parts.
For this reason, in a wristwatch, in order to use a radio signal, it is necessary to have a parts configuration or design completely different from the configuration of time piece parts in the past, and additionally necessary to have a consideration be such that it does not hinder receiving performance.
Light weight, thinness, ease of portability, degree of freedom in design, mass-feeling of texture (feeling of high quality) are important issues in a wristwatch, and it is desirable to have a built-in antenna and a metal exterior parts.
In the case of a radio controlled time piece of the past, as described above, the main methods were to mount the antenna on the outside enclosure or to build in the antenna.
In the case in which the material of the caseback and sides is metal, the receiving antenna is generally mounted on the outside.
In this case, because the case of the receiving antenna is made of a non-metal such as plastic in order not to reduce the receiving performance, it is in the form of a large protrusion, thereby resulting in a great loss of compactness, thinness, and ease of portability, as well degree of freedom in design.
In the case in which the receiving antenna is built in, although ceramic or plastic is used as the material for the exterior parts (caseback and sides) of the time piece in order not to reduce the receiving performance, the low strength of this material causes the thickness of the watch to increase, thereby sacrificing storability and ease of portability, and imposing a great restriction in terms of design.
Additionally, the result is a wristwatch having little mass-feeling of external texture.
For this reason, as seen for example in Japanese Unexamined Patent Publication No. 2-126408, there is the case in which a metal antenna is disposed within the leather band of the watch.
Further, as disclosed in the Japanese Unexamined Patent Publication No. 5-81787, there is a time piece in which an antenna with a coil wound around a core is disposed between the watch dial and the wind shield, not only removing it from the metal case itself, which interferes with radio signals, but also providing a unique design and, in the international publication WO 95/27928, there is disclosure of a wristwatch having a configuration in which an antenna is mounted to a side part of the watch case.
Additionally, as disclosed in European patent laid open 0382130, there is a time piece in which an antenna is disposed in, for example, an annular shape, on the upper surface of the case.
However, in the configuration of the past in which the antenna is disposed in the band, because the antenna is built into the band, it is necessary to make electrical connection with the electronic device itself, and it is not possible to impart sufficient flexibility to the joining part between the two.
Additionally, because it is not possible to use a metallic band that would interfere with radio signals, it is necessary to use a special watch band, this imposing a restriction on material and design.
Additionally, in a time piece configured with the antenna is disposed on the upper surface or on a side surface thereof, because the antenna is distanced from the metallic part of the time piece itself, there is the problem of an increase in the thickness or size of the overall time piece and the imposition of a design restriction.
Additionally, in the watch in European patent laid open 0382130, in which the antenna is disposed in the shape of a ring on the upper surface of the case, there is the problem that, if metal is present within the ring part, because reception cannot be performed, making it essentially necessary to provide an antenna that is separate from the time piece.
Additionally, although in the Japanese Unexamined Patent Publication No. 11-064547 there is disclosure of a wristwatch in which a coil is disposed in a sunken part provided in a peripheral part of a circuit board and also a core is disposed in a curved shape along the circumferential direction of the printed circuit board, this results in the problems of not only complication of the manufacturing process, but also difficult assembly in the manufacturing process.
In the Japanese Unexamined Patent Publication No. 2001-33571 or the Japanese Unexamined Patent Publication No. 2001-30524 and the like, there is indicated a wristwatch with a configuration in which the wind shield and caseback parts of a wristwatch is made of a non-metallic material such as glass or ceramic, and in which an intermediate portion thereof is made of a metal material such as in the past, so that sufficient radio signals can reach the antenna.
The Japanese Unexamined Patent Publication No. 2001-208875 discloses technology regarding an identification tag for a wristwatch, the basic technical constitution of the identification system disclosed being one in which, when boarding a ski lift or the like, an identification tag is provided within the wristwatch held by a user, and in which information is exchanged with an identifying means provided at the lift boarding gate, so as to determine whether or not the user is an authorized passenger.
However, the basic technical concept of the technical constitution in this patent publication is one of a strong, high-frequency radio signal being transmitted from the identifying means, the wristwatch having the identification tag coming into proximity thereto so that an IC circuit within the wristwatch is activated, with identification tag information being read by the identifying means.
That is, in the above-noted publication the configuration is one in which, when an antenna provided within the time piece receives the high-frequency radio signal, resonance occurs in the IC circuit within the time piece, resulting in reception of electromotive force by the IC circuit and activation thereof, and reading of the identification tag information within the time piece, with radio notification being made to the identifying means.
In this patent publication, therefore, although there is teaching of conversion of the above-noted information by operation of the antenna provided within even a watch having a metal exterior parts, the clear difference in technical concept relative to this application is the provision of an identifying means transmitting a high-power frequency radio signal and the need for the time piece having an identification tag to come into the vicinity of the identifying means, the antenna provided within the time piece being based on a bar antenna so that sufficient reception is possible of the high-frequency radio signal transmitted from the identifying means, and because of the need to make this, within the watch, as thin and as large as possible, there is the need to use a square antenna of the thin, flat type, this clearly differing from the present application, which sets forth a specific relationship between the antenna part and the metallic exterior parts.
Additionally, in the Japanese Unexamined Utility Model Publication No. 57-131042, there is language with regard to a wristwatch in which an antenna is provided that uses an annular magnetic bar that is a C-shaped ferromagnetic body surrounding a conductor part. However, this known example is with regard to an antenna for a wristwatch having a radio, and the antenna is merely disposed on the outside of the wristwatch, making it clear that it not provided inside a metal exterior parts.
Additionally, although in the Japanese Unexamined Patent Publication No. 6-215942, there is language to the effect of an core of an inductor being a separate member, this is directed at a chip inductor, and not only does this clearly differ in technical field from the antenna of a wristwatch in the present invention, but also there is a substantial difference in terms of purpose and technical constitution.
In the Japanese Unexamined Patent Publication No. 11-74138, although there is language regarding a transformer in which a dust core is a combination of a U-shaped member and an I-shaped member, with a secondary coil wound around the U-shaped member, this is directed at obtaining a high-voltage transformer, and not only does this clearly differ in technical field from the antenna of a wristwatch in the present invention, but also there is a substantial difference in terms of purpose and technical constitution.
In the same manner, although in the Japanese Unexamined Utility Model Publication No. 61-203516, there is disclosed a structure in which the abutting surface of a core is caused to be inclined from the perpendicular magnetic path direction, this is directed at obtaining a inductance element, and not only does this clearly differ in technical field from the antenna of a wristwatch in the present invention, but also there is a substantial difference in terms of purpose and technical constitution.
In the Japanese Unexamined Patent Publication No. 2002-184637, there is found language regarding making the gap of the coil core tapered or changing the surface area, this known example being with regard to a high-voltage transformer, and not only does this clearly differ in technical field from the antenna of a wristwatch in the present invention, but also there is a substantial difference in terms of purpose and technical constitution.
Additionally, although in the above-noted known references, a language is found regarding a configuration in which making the core of the inductor a separate member, this is with regard to a high-voltage transformer or chip inductor, and not only does this clearly differ in technical field from the antenna of a wristwatch in the present invention, but also there is a substantial difference in terms of purpose and technical constitution.
That is, the above-noted examples in the past are based on the sharp decrease in the output of an antenna when housed in a metal exterior parts, the object thereof being the decrease in output being reduced by making the material of the caseback non-metallic, and to use the metal side that has a high mass-feeling of texture.
However, in the above-noted examples of the past, because glass or ceramic is used, there is the problem of the watch thickness increasing.
In the past, therefore, because a large, high-sensitivity antenna structure should be used for a radio controlled time piece or the radio controlled time piece can be possible to use only in a region in which the radio signal field strength was large, its convenience has been lost, and thus there was an inevitable increase in the manufacturing cost of the antenna structure, including the design of the physical antenna.
Furthermore, in a wristwatch having this configuration, even if it is possible to have a radio signal reach the antenna, although the caseback is plated with a thin metallic plating so that the user is given the impression that a metal material has been used, there is no sense of weight or mass-feeling of texture in the outer appearance, and the problem of sacrificing the image of the time piece as being of high quality.
Additionally, because the antenna is built into the metal side, the output of the antenna decreases, and the receiving performance decreases.
For this reason, in the past a radio controlled time piece with a totally metal exterior parts having a feeling of high quality was difficult to achieve.
In order to solve these problems with the prior art, the inventors, in Japanese Patent Application 2001-297095, have already identified the problem that, when an antenna is disposed in a time piece enclosure having metal sides or a metal caseback, the Q value decreases, resulting in a decrease in the output from the antenna structure and a prominent decrease in receiving performance, and to solve this problem proposed a technical constitution in which the antenna is given a special structure, so that the decrease in the Q value of the antenna structure is minimized as much as possible, thereby preventing a decrease in the receiving performance of the antenna.
However, in the method of imparting a specific structure to the antenna, because it was learned that there is a limit to the improvement in the receiving performance of the antenna structure, as a result of further active investigation, it was learned that by specifying the structure or characteristics of a metal exterior parts that includes the antenna structure, there is a further improvement of the above-noted problem.
Additionally, as a result of active investigation, verification was made that, with regard to the idea in the past that, in the case in which a metal object having electrical conductivity comes into the vicinity of or into contact with the antenna part for receiving radio signals, the radio signal is absorbed by the metal object, and the radio signal does not reach the antenna part, so that there is a decrease in the resonant output of the antenna part and, for example, there is a decrease in the Q value, the understanding of the problem in the past was in fact mistaken, and that even in the case in which a metal object having electrical conductivity comes into the vicinity of or into contact with the antenna part, a radio signal actually reaches the antenna part, and in the non-resonant case the flow of magnetic flux due to an external radio wave attempting to enter to within the time piece, although somewhat attenuated (approximately 3 dB, for example), the signal substantially reaches the antenna without hindrance.
It was clearly identified that the problem when the antenna part is in resonance is that the magnetic force lines (magnetic flux) emanating from the magnetic core of the antenna part are pulled into the metal object, wherein they cause eddy currents that attenuate the magnetic energy, resulting in the problem of a reduction in the output from the antenna part, and prevention of normal reception.
That is, in the radio controlled time piece of the past as noted in FIG. 21, although there is no great problem radio signal receiving performance when using it portably, because a glass 23 is fixed to the peripheral frame 22 of the caseback 12, if the wristwatch is dropped, for example, so as to impart an impact thereto, there is the problem that the glass 23 breaks. Additionally, because the caseback 12 is in intimate contact with a wrist, over long periods of use perspiration and the like can cause the glass 23 can become removed from the peripheral frame 22, and there is a significant risk that perspiration, water, and dust and the like can intrude into the movement of the wristwatch (antenna 1, radio-controlled watch receiver 2, CPU 3, and display drive section 4 and the like), thereby causing a prominent reduction in functioning as a wristwatch.
Additionally, because the caseback 12 is provided with the glass 23, in addition to an increase in the number of parts, there is the problem of an increase in the number of assembly steps and an increase in cost. Because a non-metallic member is used in the exterior parts, the wristwatch lacks a feeling of weight, and has problems with regard to a feeling of high quality and feeling of attractiveness as well.
The present invention was made in consideration of the above-noted problems in the prior art, and rests in the provision of an electronic device that, even in the case of a conventional metal case, is capable of receiving prescribed information, such as time information with no problem during portable use, and further that has waterproofness quality, and not only provides an improvement in the quality of its outer appearance, but also enables an expansion of design variations in the same manner as a general type of time piece.
Additionally, the present invention has as an object to provide an electronic device that solves the above-noted problems of the past, has good radio-signal receiving performance, and has a metal exterior parts into which is built an antenna part that is not greatly subjected restrictions in terms of material or restrictions in terms of design.
A further object of the present invention, in addition to the above-noted object, when applied to a radio controlled time piece, which is one specific example of the application of the present invention to an electronic device, is not only to prevent an increase in the bulkiness of the wristwatch by an increase in the thickness thereof, but also to provide a radio controlled time piece with a good sense when worn on the wrist.
Additionally, the present invention, similar to a time piece of the past, provides a radio controlled time piece that, although using a metal exterior parts and metal caseback having a relative high permeability made of titanium or stainless steal, maintains the same type of receiving performance as with a watch case and caseback made of a high polymer or ceramic, and also is compact and thin.